Acceleration system

ABSTRACT

An acceleration system ( 30 ) for accelerating a load, for example for launching an aircraft ( 21 ), comprises a flywheel ( 12 ) driven from a power source ( 15 ), the flywheel ( 22 ) having a spiral profiled surface ( 16 ) for receiving a cable ( 17 ) a remote end portion of which is connectable to the aircraft ( 21 ). The profiled surface ( 16 ) ensures that launching of the aircraft ( 21 ) is effected smoothly, initially at low speed and then at progressively increasing speed until the aircraft attains take-off speed.

[0001] This invention relates to an acceleration system for acceleratinga load, and particularly, but not exclusively, to an aircraft launchingsystem.

[0002] In GB 1 145 137 A, there is described an aircraft launchingsystem comprising a cable, an end portion of which is adapted forreleasably coupling with an aircraft and a remote end portion of whichis secured. The cable is entrained in a pulley system, which includes amechanism for accelerating the cable in a longitudinal direction so asto launch an aircraft coupled to the cable. The mechanism comprises aflywheel and a two-speed transmission coupled to the flywheel by amultiple disc friction clutch. The arrangement is such that the aircraftis accelerated slowly at first, for a distance approximately a quarterof the launch distance, and then accelerates rapidly to reach take-offspeed.

[0003] In U.S. Pat. No. 1,734,353 A, there is described an aircraftlaunching system comprising a cable, an end portion of which is adaptedfor releasably coupling with an aircraft and a remote end portion ofwhich is secured. The cable is entrained in a pulley system, whichincludes a mechanism for accelerating the cable in a longitudinaldirection so as to launch an aircraft coupled to the cable. Themechanism comprises a flywheel and a gear coupling a motor to theflywheel, a drum, adapted for rotation on an axis, the surface of whichhas a curved profile the radial dimension of which increasesprogressively from the said axis in an arcuate direction of the saidaxis, and a clutch to couple the drum to the rotating flywheel. Thearrangement is such as to impart a uniform acceleration to the aircraftand have it reach take-off speed.

[0004] An objective of the present invention is to provide anacceleration system, which provides energy uniformly over a short timespan.

[0005] According to the present invention there is provided anacceleration system comprising a cable, an end portion of which isadapted for releasably coupling with a load, a rotary member adapted forrotation on an axis and drive means for disengageably engaging with therotary member so as to rotate the rotary member on the axischaracterised in that the rotary member is provided with a surface forreceiving a portion of the cable remote from the said end portion andthe surface has a curved profile the radial dimension of which increasesprogressively from the said axis in an arcuate direction of the saidaxis.

[0006] Following is a description, by way of example only and withreference to the accompanying drawings, of one method of carrying theinvention into effect.

[0007] In the drawings:

[0008]FIG. 1 is a diagrammatic representation demonstrating theprinciple of operation of an acceleration system in accordance with thepresent invention,

[0009]FIG. 2 is a diagrammatic representation of an embodiment of anacceleration system in accordance with the present invention,

[0010]FIG. 3 is a diagrammatic representation of another embodiment ofan acceleration system in accordance with the present invention.

[0011] Referring now to FIG. 1 of the drawings there is shown anembodiment of a system 10 for accelerating a load 11 in accordance withthe present invention comprises a wheel 12 rotatably mounted on an axis13 and driven, so as to rotate on the axis 13, by means of a powersource 14 acting through a drive roller 15 in contact with a peripheralsurface of the wheel 12. The wheel 12 is provided with a surface 16 forreceiving a cable 17. The surface 16, when viewed axially of the axis13, is of a curved formation, the profile of which extendinglongitudinally of the surface 16 and in a radial direction from the axis13 increases progressively from the axis 13 in an arcuate direction ofthe axis 13. The cable 17 is guided around a pulley 18 which is freelyrotatably mounted on an axis 19 located above the wheel 12 and an endportion of the cable 17 is adapted to be locatable on the axis 13. Means(not shown) is provided for pushing the cable 17 towards the wheel 12 inan axial direction of the wheel 12.

[0012] In a starting position, an end portion of the cable 17 remotefrom the axis 13 is connected to the load 11 while the distal end of thecable 17 is held away from the profiled surface 16 of the wheel 12. Thepower source 14 is then operated so as to rotate the wheel 12. When therotational kinetic energy is sufficient to provide power to acceleratethe load 11, then the said means is operated to push the distal end ofthe cable 17 towards the wheel 12 so that the distal end of the cable 17locates on the profiled surface 16, the end portion of the cable 17remote from the load 11 being restrained at the centre of the wheel 12.

[0013] The effect of the profile of the surface 16 is such that thecable 17 draws the load 11 in a direction towards the pulley 18,initially at low speed and then at progressively increasing speed as theradial distance of the profile of the surface 16 from the axis 13increases.

[0014] Means would be provided for disengaging the drive roller 15 fromthe wheel 12 and for braking the wheel 12 after the load 11 has beenlaunched.

[0015] Referring now to FIG. 2 of the drawing there is shown anembodiment of a system 20, in accordance with the present invention, forlaunching an aircraft 21. The system comprises a wheel 22 rotatablymounted on an axis 23 and driven, so as to rotate on the axis 23, bymeans of a power source 24 acting through a clutch 29. The wheel 22 isprovided with a surface 28 for receiving a cable 27. The surface 28,when viewed axially of the axis 23, is of a curved formation, theprofile of which extending longitudinally of the surface 28 and in aradial direction from the axis 23 increases progressively from the axis23 in an arcuate direction of the axis 23. The other end portion ofcable 27 is turned on an additional rotary member 25, which is adaptedfor rotation on a second axis. A second cable 26 is attached on one ofits end portion to the additional rotary member and is connected on itsother end portion to the aircraft 21. Means (not shown) is provided forpushing the cable 27 towards the wheel 22 in an axial direction of thewheel 22.

[0016] In a starting position, an end portion of the cable 27 remotefrom the axis 23 is connected to the aircraft 21 while the distal end ofthe cable 27 is held away from the profiled surface 28 of the wheel 22.The power source 24 is then operated so as to rotate the wheel 22. Whenthe rotational kinetic energy is sufficient to provide power toaccelerate the aircraft 21, then the said means is operated to push thedistal end of the cable 27 towards the wheel 22 so that the distal endof the cable 27 locates on the profiled surface 28, the end portion ofthe cable 27 remote from the aircraft 21 being restrained at the centreof the wheel 22.

[0017] The arrangement is such that the drum 25 is of lighterconstruction than the wheel 22 and may be arranged such as toaccommodate the length of the cable 26 more easily than the profiledsurface 28.

[0018] Referring now to FIG. 3 of the drawing there is shown anembodiment of a system 30 which operates in accordance with theprinciple described with reference to FIG. 1 except that, instead ofbeing locatable on the axis 13, an end of the cable 17 is provided witha ball 31 and the wheel 12 is provided with a pair of spaced protrusions32, 33 located adjacent a centre of the wheel 12.

[0019] The arrangement is such that, in a starting position, the wheel12 rotates on the axis 13 and the portion of the cable 17 extending fromthe pulley 18 to the ball 31 is located a short distance away from thewheel 12. Means (not shown) is then operated to push that same portionof the cable 17 towards the wheel 12 so that the cable 17 is locatedbetween the protrusions 32, 33 but is prevented by the ball 31 fromrunning out through the gap between the protrusions 32, 33. The cable17, therefore, is entrained around the profiled surface 16 of the wheel12 as the wheel rotates.

[0020] The axis 13 may comprise a tube and the cable 17 may be guidedthrough the tube. Such an arrangement provides for separation of thecable 17 from the wheel 12 at a location of reduced angular speed. Theremay also be provided means (not shown) separate from the wheel 12, forrotating on the axis 13 and adapted to rotate at the same speed as thewheel 12 for drawing the cable 17 in a direction normal to the plane ofthe wheel 12. The arrangement would be such that, when the cable 17 hasbeen drawn off the profiled surface 16 of the wheel 12 and onto the saidmeans, the said means can be slowed and stopped independently of thewheel 12 and the cable 17 can be returned to a starting position.

[0021] The wheel 12, being separate from the said means, isreaccelerated immediately after launch of the aircraft 21 so as torestore lost energy while the cable 17 is returned to the startingposition.

[0022] It will be appreciated that, while the invention is particularlyadapted for launching aircraft, it may also be suitable for otherapplications, such as for launching targets in a firing range.

[0023] The invention may also be suitable for other industrialapplications, for example for propelling motor vehicles in crashtesting.

[0024] It will be appreciated that an acceleration system in accordancewith the present invention is simpler and more economic thanhigh-pressure steam operated systems known hitherto.

1. An acceleration system comprising a cable (17), an end portion ofwhich is adapted for releasably coupling with a load (11), a rotarymember (12) adapted for rotation on an axis (13) and drive means (15)for disengageably engaging with the rotary member (12) so as to rotatethe rotary member (12) on the axis (13), and the rotary member (12) isprovided with a surface (16) for receiving a portion of the cable (17)remote from the load (11), and the surface (16) has a curved profile,the radial dimension of which increases progressively from the said axis(13) in an arcuate direction of the said axis (13), characterised inthat there is provided means for engaging a portion of the said cable(17) remote from the load (11) with the said rotary member (12), whilethe said rotary member (12) is rotating, so that the portion of the saidcable (17) remote from the load (11) locates on the said surface (16)while an end portion of the said cable (17) remote from the load (11) isrestrained at a location on the rotary member (12) adjacent to a centreof the rotary member (12).
 2. An acceleration system comprising a cable(26), an end portion of which is adapted for releasably coupling with aload (21), a rotary member (22) adapted for rotation on an axis (23) anddrive means (24) for disengageably engaging with the rotary member (22)so as to rotate the rotary member (22) on the axis (23), and anadditional rotary member (25) adapted for rotation on a second axis, andan end portion of the said cable (26) remote from the load (21) isattached to the additional rotary member (25), and a second cable (27),an end portion of which is attached to the addititional rotary member(25), and the rotary member (22) is provided with a surface (28) forreceiving a portion of the said cable (27) remote from the additionalrotary member (25), and the surface (28) has a curved profile, theradial dimension of which increases progressively from the said axis(23) in an arcuate direction of the said axis (23), characterised inthat there is provided means for engaging a portion of the said cable(27) remote from the additional rotary member (25) with the said rotarymember (22), while the said rotary member (22) is rotating, so that theportion of the said cable (27) remote from the additional rotary member(25) locates on the said surface (28) while an end portion of the saidcable (27) remote from the additional rotary member (25) is restrainedat a location on the rotary member (22) adjacent to a centre of therotary member (22).
 3. An acceleration system as claimed in anyone ofthe preceding claims characterised in that the drive means (24) includesa clutch mechanism (29).
 4. An acceleration system as claimed in anyoneof the preceding claims characterised in that the said engaging meansincludes a pair of spaced protrusions (32,33) located at an end of thesaid cable (17) remote from the load (11).